This post is the second in a series introducing you to under-utilized, advanced training techniques. As I explained in my last post on constant tension timed sets, the key to steady growth without plateaus is to force your neuromuscular system to adapt to a continuously changing set of stimuli.

These training techniques that I’m talking about this month are not unheard of and were not created by me, but they’re generally only used and understood by more advanced bodybuilders and their coaches. These are all techniques that Ryan and I only use with our personal one-on-one clients, because they do require precision, oversight and careful monitoring in order to work safely and reap the best results.

This post, I want to talk to you about an incredibly effective technique for targeting functional hypertrophy: hypertrophy cluster sets. You may have also heard this technique referred to as rest-pause training.

What are Hypertrophy Cluster Sets?

Hypertrophy cluster sets are a technique that uses very short, inter-set rest periods to enable you to stimulate recruitment of fast-twitch muscle fibers before you fatigue the muscle. Those rest periods enable you to do more reps than you ordinarily would and to stimulate the Type 2 muscle fibers, which usually are not recruited until after the Type 1 muscle fibers have been fatigued.

Let me give you a quick understanding of what I mean by this.

Type 1 muscle fibers are engineered for endurance. They are responsible for a low amount of strength and power, but they’re main task is getting you through the long haul, so they’re slow to fatigue. Type 2 muscle fibers are mainly for strength and power. They’re to give you that burst of explosive power that you need to get through the task when your Type 1 fibers begin to fail.

Using a standard protocol of 8-10 reps at a load of 70-80% of your one rep max, only the slow twitch (or Type 1) muscle fibers are recruited. It’s only after these muscle fibers reach fatigue that your brain signals the Type 2 fibers to kick in and help. Unfortunately, with this standard training method, you stop lifting when that point of fatigue is reached.

Functional hypertrophy training using cluster sets allows you to recruit Type 2 fibers earlier and do more reps than you would with a standard protocol of 8-12 reps, rest, 8-12 reps and so on.

Why is this important?

Each muscle fiber has two parts: the sarcoplasm and the sarcomere. When you’re working only the Type 1 muscle fibers, you experience sarcoplasmic hypertrophy, which increases the amount of fluid and non-contractile proteins in the muscle fibers. It doesn’t do much for strength, but it makes you look good because it pumps up the muscles.

On the other hand, when you’re recruiting Type 2 muscle fibers, you get sarcomere hypertrophy, which is also called functional hypertrophy. It’s called functional hypertrophy because it increases the function of the muscle, but also increases the efficiency of neuromuscular signaling, making it faster and easier for your brain to recruit these fibers next time. Sarcomere or functional hypertrophy increases the contractual proteins in the muscle and the actual number of sarcomeres in the muscle fiber. This means greater strength, greater power and greater size.

The standard protocol of set/rest/set lacks the intensity needed to recruit those Type 2 fibers and stimulate functional hypertrophy. In order to get that intensity level, you need to be able to do more reps, which means you have to stimulate recruitment of Type 2 fibers before you’ve fatigued the Type 1 fibers. This is where the inter-set rest periods come in.

How It’s Done

For this example of functional hypertrophy clusters, you would select your 7-8-rep max to begin. A typical workout of 5 sets of 4+4+4 with 3-minute rest periods might go like this: you do four reps, rest for 10 seconds, do four more, rest for 10 seconds, do four more rest for 3-minutes and then do your remaining sets. If you can complete all three mini-sets with the prescribed reps, increase the weight 10% and start over. As the loads becoming more challenging a typical workout might look like four reps, rest 10 seconds, 3 reps, rest 10 seconds and then 2-3 reps and then rest 3-minutes. As you become stronger, you’ll be able to achieve 4+4+4, which is a total of 12 reps with a load originally your 7-8 rep max. Can you say, Awesome-Sauce! This is sufficient volume and intensity to move you into functional or sarcomere hypertrophy.

Functional hypertrophy clusters are not appropriate for every exercise. They’re best done with barbells so that you can rack the weight during your rest period and they work best with large, compound movements. They’re also too high an intensity level for long-range work. They should be done for a couple of weeks prior to a scheduled deloading phase to keep you from frying your neurological system.

However, when utilized properly and done correctly, hypertrophy cluster sets will not only get you serious results as far as size, but improve the efficiency of your neuromuscular communication, making it easier to continue this level of growth every time you use this method.

I do need to stress again, though, that this type of training is not for beginning bodybuilders. This is for guys who are at an intermediate level, who have been training regularly, with regular progression, for at least a year or two. This is why Ryan and I generally only employ this technique with our one-on-one clients, who have made an investment in their training because they’re serious about what they’re doing and ready to take their training to the next level and we can carefully prescribe the correct amount of load and volume based on their previous experiences.

What to Do Next

If you genuinely feel that you’re ready to take on this kind of high-intensity protocol, then talk to your coach or trainer about doing functional hypertrophy clusters. I strongly advise that you do this only if your coach is familiar with this method and has used it with other clients.

If you don’t have a coach or trainer, then I would strongly urge you to either wait on trying this training method or take a look at our personal, one-on-one training program.

I sincerely don’t advise incorporating functional hypertrophy clusters on your own and our one-on-one coaching is an affordable investment that will give you the knowledge and supervision you need for this and many other advanced training techniques that guarantee incredible results without having to deal with plateaus.

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